Now that I know the thing works I want to be able to move this into my living room, keeping this in the garage is not ideal, it is not the most ideal environment for it with temps pushing 100f in the summer and high 30's in the winter. To do this I really needed to get rid of the diffusion pump, it sway 400w at 100v and most of that heat needs to be removed with a air/water heat exchanger. Not only is it noisy it also take up space. To eliminate this I got a Varian Navigator 301 turbo pump and control from a friend as well as an Edwards XDS10 dry scroll vacuum pump that I found at a scrap yard.

This has a number of advantages, it removes oil from the system. Oil is bad in a SEM in general, it gets deposited on apertures and messes up the image and it also degrades the phosphor on the SED. It also creates a big plume of oil vapor when you pump down the column after a sample change. It also reduces power consumption, not only does it eliminate the 400w heater in the diffusion pump it also eliminates the need for the cooler which is another 1/3hp electric motor. The turbo pump uses 150w at full gas load and about 7 watts at high vacuum. Quite a bit of savings!

The whole machine also comes up a whole lot faster now, with the diffusion pump you would have to wait at least 20 minutes from power-on for it to be ready to pump the chamber. With the turbo it spins up in less than a minute and running a few minutes later. This makes it much nicer to use. I was worried the turbo would be too small, the diff pump was rated at 400 l/s and the turbo at 250 but it turned out not to be a problem in the end, the turbo seems faster.

I had an adapter that mated with the turbo and fit the bolt pattern of the old pump and it went together pretty well. I did add a vacuum reservoir on the foreline of the turbo to give it a little buffer, I think I might have a leak on one of the roughing valves on the system, I get a pressure spike when I vent the chamber.

I picked up a couple ISO100 vibration isolators for the turbo and install one of those. I may need to shorten the pump adapter in the future to make it fit better.

With these modifications done I brought the SEM into the living room. Not something I ever want to do by myself again!